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The Planetary Society returns to the Crawford Family Forum with an evening devoted to the revolutionary potential of solar sailing. It has been called the only practical way to reach the stars, but driving spacecraft across the solar system with the pressure of sunlight may offer big advantages over traditional rocket engines.

Christmas came early for space fans at KPCC’s Crawford Family Forum July 9, when about 2,600 people—including 2,400 viewers online — watched Bill Nye the Science Guy announce the culmination of a 34-year-old dream for The Planetary Society — launching a solar-powered spacecraft called LightSail into orbit in May of 2016.

“This is awesome, a very very cool thing for members of the Society and people in the public who love space exploration and follow space missions,” said Planetary Society President Jim Bell, professor of planetary sciences at Arizona State University, who practically bounced in his chair as he discussed the project.

Turning to Nye, Bell grabbed his arm and crowed, ”It’s a mission, man. We’re making a mission!”

The passion for solar sailing goes back to the Planetary Society’s formation in 1980, said Nye, now the Society’s CEO, “when the public interest in space exploration was high but government support was not quite that high.”

The Society’s founders — Jet Propulsion Laboratory engineer Louis Friedman, JPL manager Bruce C. Murray and astronomer/author Carl Sagan — were strong proponents of using solar power to travel through space. Nye recalled taking an astronomy class from Sagan, and how he often “spoke eloquently about sailing with sunlight.”

The founders, especially Friedman, saw solar sailing as the best hope for space exploration, because of its relative low cost and the simple fact that its fuel — light from the sun — is free.

“Solar sailing is part of the future of space exploration because it’s using this fantastic, phenomenal energy source that maybe we take for granted too much,” Bell said.

‘Yes,” quipped Nye, “a fusion reactor at a safe distance — the sun!”

“It’s just an amazingly cool thing that a group of like-minded people can get together and pool our resources to do this,” Bell said. “We’re not the U.S. government, we’re not Russia or a big international corporation. We’re just a bunch of people who love space and we’re going to put it all together and run our own mission and I think that’s awesome.”

You can watch the entire 90-minute webcast of the Planetary Radio show, led by host Mat Kaplan, in the video above. Other speakers included Doug Stetson, LightSail program manager; Barbara Plante, CubeSat engineer and the founder/owner of Boreal Space; David Brin, scientist, futurist and science fiction writer; and Jason Davis, the “embedded” journalist/blogger who the Planetary Society has hired to cover the program. You can read his work here.

Highlights:

The craft itself

The main body is a CubeSat, a kind of compact satellite that, in the case of LightSail, resembles a very fancy patio light. Plante, who is building her own CubeSat, called the design “elegant and very beautiful.”

You can see her point out the features in one of the actual crafts, right there on stage, about 41:30 minutes into the video.

Folded up, the LightSail is just 30x10 centimeters. “A little box,” Nye called it, designed and built by a team led by Tomas Svitek of Stellar Exploration. The program is making two LightSails, LightSail-A and LightSail-B, at a cost of $4 million.

LightSail’s important difference

CubeSats are fairly common satellites these days, but LightSail is unique, in that it will be able to propel itself using the energy collected from its solar sails. Once deployed, the spacecraft will unfurl its four solar sails into a 32-square-meter square, which can capture sunlight on either side and be so bright they’ll be visible on earth during certain times of the day, Nye said.

How thin is it?

Each sail is made of reinforced mylar and is “crazy thin,” Nye said, at just 4.5 microns, “about a 50th of the thickness of a human hair.” Stetson said it takes Stellar Exploration’s crew 30 minutes to hand-fold each sail panel into a triangle small enough to fit in your hand, and, not coincidentally, the tiny alcoves on the spacecraft designed to hold them. (You can see how sail is folded up, and where it fits into the CubeSat 41 minutes into the video.)

What will it do?

LightSail will orbit the earth every 90 minutes, sending photos and other data down to two listening posts, at Cal Poly San Luis Obispo and Georgia Tech. Someday, if things go well, the Society hopes to send it, or its progeny, deeper into space. Stetson noted that the German mathematician Johannes Kepler sent a letter to Galileo in 1610, which seemed to advance the idea of solar sailing: “Provide ships or sails adapted to the heavenly breezes, and there will be some who will brave even that void,” Kepler wrote.

How is LightSail getting into space?

One of the biggest hurdles to the Planetary Society’s solar sailing dream has been getting their spacecraft high enough to be outside the atmospheric drag, which would pull it back to the earth. Stetson said that’s about 20 kilometers high.

The Society hopes s to test LightSail-A in May, 2015, in the high atmosphere, to make sure that its 32 square meters of solar sails deploy correctly, but that spacecraft will eventually fall back to earth.

The big trip comes in May, 2016, when LightSail-B will hitch a ride on the privately owned SpaceX Falcon Heavy rocket, the “the most powerful rocket ever built, with the exception of the Saturn 5, which took people to the moon,” Kaplan said.

Wait, isn’t it pricey to get a seat on a rocket?

Ordinarily, yes, but LightSail-B is getting on for free, Stetson said, as part of Georgia Tech’s Prox-1 student project. LightSail will actually be closed up inside the Prox-1, and deployed once it reaches space. (You can see artist renderings of what it’s supposed to look like about 28:10 minutes into the video.)

The Prox-1 project is designed to show that that Georgia’s Tech Prox-1 spacecraft can operate close to another spacecraft, so the LightSail project fits the bill perfectly, Stetson said. Prox-1 can perform its maneuvers around LightSail, and the data from Prox-1 will give Planetary Society’s scientists lots of information about how the solar sails deploy and operate in space.

“Really,” Stetson said, “it was a match made in heaven because it’s giving us a free launch, which goes to show there is a free launch after all.”